1. Field of the Invention
This invention relates to a method for the production of an alkylamino(meth)acrylate and an apparatus therefor. More particularly, it relates, in the production of an alkylamino(meth)acrylate by the reaction of transesterification of a corresponding alkyl(meth)acrylate with an alkylamino alcohol, to a method for the purification of an alkyl alcohol by-produced in the transesterification, a method for handling the purified alkyl alcohol, a method for the purification of the reaction solution resulting from the transesterification, and an apparatus for the method of purification.
2. Description of the Related Art
The production, by the reaction of transesterification of an alkyl(meth)acrylate represented by the formula (1): 
with an alkylamino alcohol represented by the formula (2): 
of an alkylamino(meth)acrylate represented by the formula (3): 
wherein the symbols are defined as described herein below, itself has been heretofore known from JP-A-4-95,054. This method consists in performing the reaction of transesterification while having the concentration of the alkylamino alcohol in the reaction system adjusted to not more than 25 mol %.
JP-A-5-85,997 describes, as a method for the production of a dialkylamino alkylacrylate, the reaction of transesterification which uses a dialkyl tin oxide as a catalyst and n-butyl acrylate as an alkyl acrylate and distills the reaction product under a reduced pressure to expel a by-produced n-butanol.
JP-A-3-112,949 discloses, concerning the recovery of a catalyst from the reaction solution obtained by the reaction of transesterification, a method which consists in distilling the reaction solution in the absence of oxygen.
JP-A-6-271,517 discloses a method for producing the alkylaminoalkyl ester of (meth)acrylic acid by the reaction of transesterification of a (meth)acrylic ester with an alkylamino alcohol.
JP-A-6-256,271 discloses a method for recovering by distillation a by-product which occurs during or remains after the production of the alkylamino alkyl ester of (meth)acrylic acid by the reaction of transesterification of a (meth)acrylic ester with an alkylamino alcohol.
JP-A-54-163,517 discloses a method which comprises a first step of performing a reaction of transesterification of the alkyl ester of (meth)acrylic acid with a dialkylamino alkanol, a second step of distilling the reaction mixture obtained by the first step thereby expelling the unaltered raw materials boiling at low temperatures, and a subsequent step of subjecting a mixture having a dialkylamino alkyl(meth)acrylate concentration of not less than 90% and obtained by the second step to distillation under a reduced pressure at a temperature in the range of 60-100xc2x0 C.
Since the reaction of transesterification is an equilibrium reaction, it is caused to proceed simultaneously with the expulsion of the by-produced alkyl alcohol from the reaction system by distillation. In a commercial operation of this reaction, the expulsion is attained by providing a reaction vessel with a distillation column or tower (which will be referred to in the present invention as xe2x80x9calcohol distillation columnxe2x80x9d) and allowing the by-produced alkyl alcohol to emanate in the form of an azeotropic mixture with an alkyl(meth)acrylate from the top of the column. Then, the distillate from the alcohol distillation column is further distilled, as occasion demands, to effect the recovery of the alkyl alcohol in the form of an azeotropic mixture with an alkyl(meth)acrylate via the top of the column and the recovery of the bottoms substantially comprising the alkyl(meth)acrylate via the bottom of the column, and the substances thus recovered are circulated to the reaction vessel and used again for the reaction of transesterification.
Since the alkyl alcohol recovered as described above (which will be occasionally referred to as xe2x80x9crecovered alkyl alcoholxe2x80x9d) contains an alkyl(meth)acrylate, it is generally used as an alcohol moiety for the production of the alkyl(meth)acrylate by the reaction of esterification. When the plant for the production of the alkyl(meth)acrylate and the plant for the transesterification reaction are located at one site or at sites approximating closely to each other, these substances are stored severally in intermediate tanks when necessary and then conveyed by such means as pipes to the plant for the production of the alkyl(meth)acrylate. When the two plants are located at a great distance from each other, the substances may be stored as in storage tanks and transported by such means as tank lorries to the plant for the production of the alkyl(meth)acrylate.
When the recovered alkyl alcohol mentioned above is used as the alcohol moiety for the production of the alkyl(meth)acrylate, however, it has tended to induce degradation of the strongly acidic ion-exchange resin popularly used as a catalyst for esterification in the production of the alkyl(meth)acrylate and bring about such problems as impairing the yield of the alkyl(meth)acrylate aimed at and degrading the purity of the recovered alcohol after its storage for a certain duration.
An object of this invention, therefore, is to provide, for the operation of producing an alkylamino(meth)acrylate by the reaction of transesterification of an alkyl(meth)acrylate with an alkylamino alcohol, a method for recovering the alkyl alcohol by-produced during the reaction in a form ideal for use in the production of an alkyl(meth)acrylate, incapable of inducing degradation of purity during storage, and excellent in the stability of storage, a method for handling the recovered alkyl alcohol, and an apparatus therefor.
On the basis of the knowledge that, as taught in JP-A-4-95,054, the yield of the alkylamino(meth)acrylate aimed at is lowered during the reaction of esterification by the so-called Michael type addition reaction of the alkylamino alcohol as a raw material with the alkyl(meth)acrylate as a raw material or with the alkylamino(meth)acrylate produced, we have proposed a method for performing the reaction while keeping the concentration of the alkylamino alcohol in the reaction system adjusted to not more than 25 mol %. By this method, the reaction in process can be effectively prevented from entailing a secondary reaction.
It has been found, however, that since the alkyl(meth)acrylate, alkylamino alcohol, and alkylamino(meth)acrylate are distilled out of the reaction solution sequentially in the order mentioned even during the separation of the catalyst from the reaction solution by distillation, and, consequently, the alkylamino alcohol and the alkylamino(meth)acrylate are retained in a heated state during the interval between the termination of the distillation of the alkyl(meth)acrylate and the completion of the distillation of the alkylamino alcohol, such secondary reactions as the Michael addition of the alkylamino alcohol with the alkylamino(meth)acrylate tend to occur and, as a result, the yield of the alkylamino(meth)acrylate aimed at is lowered.
Another object of the invention, therefore, is to provide, for the operation of separating the catalyst from the reaction solution by distillation during the production of an alkylamino(meth)acrylate by the reaction of transesterification of an alkyl(meth)acrylate with an alkylamino alcohol, a method for producing the alkylamino(meth)acrylate in a high yield by effectively preventing secondary reactions and an apparatus therefor.
One aspect of the invention is directed to the provision of a method for producing an alkylamino(meth)acrylate by carrying out the reaction of transesterification of an alkyl(meth)acrylate with an alkylamino alcohol in the presence of a catalyst, characterized by causing the alkyl alcohol by-produced during the transesterification to be distilled in the form of an azeotropic mixture with the alkyl(meth)acrylate and purifying the resultant azeotropic mixture with an ion-exchange resin thereby recovering the alkyl alcohol.
Another aspect of the invention is directed to the provision of a method for the handling of the purified alkyl alcohol mentioned above, which consists in handling the purified alkyl alcohol at a temperature in the range of 0-50xc2x0 C.
A further aspect of this invention is directed to the provision of an apparatus for the production of an alkylamino(meth)acrylate, characterized by comprising a transesterification reaction vessel (A) for carrying out the reaction of transesterification of an alkyl(meth)acrylate with an alkylamino alcohol in the presence of a catalyst while removing a by-produced alkyl alcohol from the top thereof as a distillate, an alcohol distillation column (B) for removing the by-produced alkyl alcohol, which emanates from the transesterification reaction vessel (A), in the form of an azeotropic mixture with the alkyl(meth)acrylate through the top thereof, and an ion-exchange resin purifying column (D) for purifying the mixture, which emanates from the alcohol distillation column (B), thereby recovering the alkyl alcohol.
In the present invention, the alkyl acrylate and the alkylmethacrylate will be referred to collectively as xe2x80x9calkyl(meth)acrylate.xe2x80x9d
Since the purified alkyl alcohol obtained by the method of production, method of handling, and apparatus therefor according to the invention has a decreased content of the basic nitrogen compound fated to poison the catalyst for the production of the alkyl(meth)acrylate, it can be satisfactorily utilized as an alcohol moiety for the production of the alkyl(meth)acrylate.
Further, since the purified alkyl alcohol obtained by the method of production, method of handling, and apparatus therefor according to the invention can prevent the alkyl alcohol and the alkyl(meth)acrylate contained therein from inducing a secondary reaction, it excels in stability of storage and enjoys stable storage for a long time at no sacrifice of purity.
By the method and apparatus according to the invention, the alkylamino(meth)acrylate can be produced with a high yield.
By the method and apparatus according to the invention, the formation of a viscous substance in the reaction solution can be repressed and the extraction of the catalyst from the distillation column can be attained easily.